1. Field of the Invention
The present invention relates to a self-timer device for a motion picture camera, more particularly, for controlling the timing of the start and the stop of the camera release, namely, the time interval from the automatic photographing setting to the actual start of the photographing and the time interval from the start to the stop of the photographing so as to enable the automatic photographing.
2. Description of the Prior Art
A self-timer device for a motion picture camera which is so designed as to stop the camera release automatically after the elapse of a certain determined time from the start of the camera release to take pictures of one scene automatically has already been proposed.
The proposed self-timer device comprises a locking member for keeping the camera in the released state, by locking the release member in the operation position for the camera release at the time of operating the shutter release member and a lock release member for terminating the camera release by releasing the locking of the release member by means of the locking member, working upon the locking member after the elapse of a certain determined time from the start of the camera release. In this manner, the locking member locks the release member in the operation position when the release member is operated so as to start to photograph while at the same time the above mentioned lock release member is moved, driven by means of the camera driving device in such a manner that, after the elapse of a certain determined time, the locking of the release member by means of the locking member is released by means of this lock release means. Accordingly the release member is returned to the non-operation position so as to terminate the photographing.
However, as in the case with the self-timer device for photographic camera, a part of the purpose of providing a camera with a self-timer is that the photographer himself can take part in the scene, whereby by means of the proposed self-timer the photographer who operates the release member can only take part in the scene on the way so that the scene reproduced is unnatural, which is inconvenient.
Thus, quite recently, a self-timer unit which can control not only the time interval from the automatic photographing setting to the actual start of photographing (hereinafter called the waiting time), but also the time interval from the start to the termination of photographing (hereinafter called the actual photographing time) is proposed and brought on the market as one accessary unit for a motion picture camera.
On example of such is so designed that an electrical timer circuit capable of controlling both the waiting time and the actual photographing time is provided so as to control the timing of the opening and the closing of the switching means connected to the electromagnetic release device by means of the output of the timer circuit, whereby after the elapse of the waiting time, the release device is actuated so as to start photographing, while after the elapse of the actual photographing time the operation of the release device is stopped so as to terminate the photographing.
Another such example is a pure mechanical one and so designed that the control member for controlling the timing of the start and the stop of the camera release is driven by means of the force of a spring member as driving source through the governer mechanism so as to carry out the automatic photography.
However, in the case of the former one, it is necessary to provide a plural number of the time constant means for determining the time intervals in the timer circuits, so that the circuit construction becomes complicated. In the case of the latter one, the composition of various mechanisms also becomes complicated while the force of the spring member is not sufficient as the driving source of the self-timer device. Accordingly, the time intervals to be determined will fluctuate so greatly that the actual photographing time is unstable.
In view of the above mentioned short-comings of the conventional devices, the inventors of the present invention have proposed as per U.S. patent application Ser. No. 595,008 (filing date: July 11, 1975) a self-timer device by means of which only the waiting time is determined by means of an electrical timer circuit while the actual photographing time is determined by the number or the amount of the rotations of the motor for driving the film feeding device as well as the shutter device.
However, even the device in accordance with Ser. No. 595,008 is provided with an electrical timer circuit for the purpose of determining the waiting time, whereby generally such timer circuit consists of electrical components such as condenser, resistor and transistors and therefore is easily subject to the current leakage or the change of the ambient temperature so that in case of the actual photographing the time intervals to be determined are not stable, which is not stable.
In view of the above mentioned short-coming of the formerly proposed device, the inventors of the present invention have further proposed as per U.S. patent application Ser. No. 624,340 (filing date: Oct. 21, 1975) a self-timer device for a motion picture camera including the first motor for driving the film feeding device, the shutter device and so on and the second motor for driving the zoom lens system, which self-timer device is so designed that the control member for the automatic photographing including a cam portions for controlling the timing of the start and the stop of the camera release is driven by the second motor, whereby at the time of the automatic photographing the functional engagement between the second motor and the zoom lens system is released while the cam portion of the control means is engaged with the camera release device in such a manner that the timing of the start and the stop of the camera release is controlled, the control means being driven by the second motor.
However, in accordance with the proposal as per Ser. No. 624,340 the control member (in this case a cam ring) for the automatic photographing can be functionally engaged with the cam ring for zooming in the zoom lens system in such a manner that the engagement can be released selectively, whereby at the time of the automatic photographing the functional engagement of the control member with the cam ring for zooming is released in such a manner that the control member operates alone, so that the composition of the zooming device is necessarily complicated and large by means of the provision of the self-timer.